(CNN) - Equifax, the credit reporting behemoth, said on Thursday that a massive security breach may have compromised the personal information of 143 million people.
Cyber criminals have accessed sensitive information -- including names, social security numbers, birth dates, addresses, and the numbers of some driver's licenses.
The breach occurred between mid-May and July, Equifax said. The company said it discovered the hack on July 29.
Equifax is mailing notices to people whose credit cards or dispute documents were affected.
"This is clearly a disappointing event for our company, and one that strikes at the heart of who we are and what we do," said Equifax chairman and CEO Richard F. Smith.
Equifax is one of three nationwide credit-reporting companies that track and rates the financial history of U.S. consumers. The companies are supplied with data about loans, loan payments and credit cards, as well as information on everything from child support payments to credit limits, which all factor into credit scores.